1. Field of the Invention
The present invention relates to a method and apparatus of recording an audio signal composed of several tracks on a recording medium in a manner that the tracks can be distinguished from each other in the recorded audio signal.
2. Description of the Related Art
FIG. 1 is a simplified block diagram of a conventional disk recorder. The disk recorder of FIG. 1 includes an optical pickup 11 writing/reading signal to/from a writable disk 10 such as a CD-R; an A/D converter 13 digitizing an input audio signal; a recording processor 12 converting digital audio data to corresponding writing signals suitable to disk record; a servo unit 15 controlling rotation speed of the disk 10 and conducting tracking/focusing servo operation for the pickup 11; and a controller 14 controlling all elements to conduct audio signal record according to user's request.
The disk recorder configured as above records a digital or an analog audio signal on the writable disk 10. The audio signal inputted to the disk recorder may be a series of digital audio data reproduced from a disk recording medium such as a CD-R, a CD-R/W or the like, or may be an analog audio signal reproduced from an analog medium such as a cassette tape.
When recording is requested, the controller 14 commands the recording processor 12 to start writing input data. The recording processor 12 adds redundancy data for error correction to the input digital audio data and then converts them to corresponding writing signals. The optical pickup 11 radiates a writing beam, of which intensity varies in proportion to the writing signals, onto the writable disk 10.
If an analog audio signal is inputted, it is converted to digital data by the A/D converter 13 and is then applied to the recording processor 12. The recording processor 12 records the converted digital data on the writable disk 10 through the aforementioned operations.
The disk recorder records an entire input audio signal as a single track regardless of how many tracks (i.e., songs) the input audio signal includes. For example, as shown in FIG. 2, if recording is requested at p1 after audio data are inputted, all tracks #m, #m+1, #m+2, . . . on an original medium are recorded as a single track #k on a copy medium. In the example of FIG. 2, the recorded single track #k includes latter part of track #m, and several tracks thereafter of an original medium.
In the example of FIG. 3 for an analog input, tracks #m, #m+1, . . . , which have been distinguished each other on an original medium, are copied as a single track #k onto another medium from recording start p2 until the recording stops.
Because several tracks are recorded as a single track as aforementioned, inner tracks inside the single track can not be indexed with an individual track number. Therefore, the number of tracks are not matched with actual songs recorded on a copy medium. Because of that mismatch, the inner track, previously indexed by #m+1, can be played back through several manual advance skips or by tedious waiting after the track #k is played back.
For resolving such a problem, an intelligent recording method has been proposed. The intelligent method, in case that track information is received together with digital audio data, checks the track information to know whether track of input audio data is changed or not, and records audio data following the recorded input data as a next track to distinguish respective tracks when the track information is indicative of track change in a series of audio data.
Track change in recorded data can be identified by information written in sub-Q code column of subcode block each 8 bits of which are inserted in audio data periodically at a given interval, as shown in FIG. 4 showing compact disk recording standard. The sub-Q column is composed of 98-bit-long frames shown in FIG. 5 and track number is written in the field ‘TNO’ of every frame. Same track number is repeatedly written in the field ‘TNO’ in successive frames until recorded audio data are changed in track.
If input data consisting of subcode block as well as audio data as shown in FIG. 4 are received, the sub-Q column is checked to know whether the track is changed or not. When the information written in the sub-Q column is indicative of a track change, the next data following the recorded data are recorded with a different track number. Consequently, a copy medium has the same recorded tracks as an original medium.
However, if input audio data from an original medium does not have track information such as subcode block or an analog audio signal is inputted from an original source, it is still impossible to distinguish respective tracks during recording, and thus, several tracks are recorded as a single track as shown in FIG. 2 or 3.